Pyridazine






 
































Nitrogen


Nuclear Quadrupole Coupling Constants


in Pyridazine


 








 


















Nitrogen quadrupole coupling constants in pyridazine were calculated on an re structure derived by Esselman et al. [1], an ralpha (electron diffraction) structure determined by Almenningen et al. [2], and on a  B3P86/6-31G(3d,3p) optimized structure (this work).  These calculated nqcc's are compared with the experimental values of Lpez et al. [3] in Tables 1 and 2.  Earlier determination of the nitrogen nqcc's had been made by Werner et al. [4].  Structure parameters are compared in Table 3.  In Table 4, ropt atomic coordinates are given.

 








In Tables 1 - 3, subscripts a,b,c refer to the principal axes of the inertia tensor, subscripts x,y,z to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the plane of the molecule.  (degrees) is the angle between its subscripted parameters. ETA = (Xxx - Xyy)/Xzz.

RMS is the root mean square difference between calculated and experimental nqcc's (percentage of average experimental nqcc).  RSD is the residual stand deviation of calibration of the B3PW91/6-311+G(df,pd) model for calculation of the efg's/nqcc's.

 








 








   







Table 1. Nitrogen nqcc's in Pyridazine (MHz).  Calculation was made on the re structure [1]. 
   










Calc.
Expt. [2]
   







14N(1,2) Xaa - 4.657 - 4.6411(19)


Xbb
1.329
1.3711(27)


Xcc
3.328
3.2700(27)


Xab 2.646 2.709(29)

 







RMS
0.042 (1.4 %)




RSD
0.030 (1.3 %)



 







Xxx
2.331
2.412(22)


Xyy
3.328
3.2700(27)


Xzz - 5.659 - 5.682(21)


ETA
0.176




z,a
20.74
21.01(16)


a,bi
30.35




z,bi*
  9.61



 







 









* The z-axis makes an angle of 9.61o with the external bisector ('bi') of the NNC angle and tilts toward the adjacent nitrogen atom.

 









 









   







Table 2. Nitrogen nqcc's in Pyridazine (MHz).  Calculation was made on the ralpha structure [1].
   










Calc.
Expt. [2]
   







14N(1,2) Xaa - 4.544 - 4.6411(19)


Xbb
1.185
1.3711(27)


Xcc
3.359
3.2700(27)


Xab 2.687 2.709(29)

 







RMS
0.132 (4.2 %)




RSD
0.030 (1.3 %)



 






   








 









   







Table 3. Nitrogen nqcc's in Pyridazine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
   










Calc.
Expt. [2]
   







14N(1,2) Xaa - 4.637 - 4.6411(19)


Xbb
1.276
1.3711(27)


Xcc
3.361
3.2700(27)


Xab 2.682 2.709(29)

 







RMS
0.076 (2.6 %)




RSD
0.030 (1.3 %)



 







Xxx
2.311
2.412(22)


Xyy
3.361
3.2700(27)


Xzz - 5.672 - 5.682(21)


ETA
0.185




z,a
21.10
21.01(16)


a,bi
30.28




z,bi*
  9.18



 







 








* The z-axis makes an angle of 9.18o with the external bisector ('bi') of the NNC angle and tilts toward the adjacent nitrogen atom.

 














Table 3. Molecular structure parameters, re [1], B3P86/6-31G(3d,3p) ropt, and ralpha [2] ( and degrees).
 







  re   ropt  ralpha








N(1)N(2) 1.3336
1.3251  1.330


N(2)C(3) 1.3302(12)
1.3314  1.341


C(3)C(4) 1.3938(12)
1.3920  1.393


C(4)C(5) 1.3761(16)
1.3792  1.375


C(3)H(3) 1.0810(3)
1.0861  1.063


C(4)H(4) 1.0802(4)
1.0843  1.063


N(1)N(2)C(3) 119.29
119.44  119.3


N(2)C(3)C(4) 123.86(4)
123.76  123.7


C(3)C(4)C(5) 116.85(3)
116.79  117.1


C(4)C(3)H(3) 121.35(6)
121.37
 124.5


C(5)C(4)H(4) 122.37(4)
122.29
 120.2


N(2)C(3)H(3)
114.87  111.8


C(3)C(4)H(4)
120.92  122.7


 








 








 




Table 4. Atomic coordinates, B3P86/6-31G(3d,3p) ropt
 







   a ()
   b ()







N(1,2) - 1.1785 0.6625

C(3,6)
0.0191 1.3170

C(4,5)
1.2234 0.6896

H(3,6) - 0.1056 2.3997

H(4,5)
2.1401 1.2688


 








 









[1] B.J.Esselman, B.K.Amberger, J.D.Shutter, M.A.Daane, J.F.Stanton, R.C.Woods, and R.J.McMahon, J.Chem.Phys. 139,224304(2013).


[2] A.Almenningen, G.Bjrnsen, T.Ottersen, R.Seip, and T.G.Strand, ActaChem.Scand. A 31, 63(1977).

[3] J.C.Lpez, A.deLuis, S.Blanco, A.Lesarri, and J.L.Alonso, J.Mol.Struct. 612,287(2002).

[4] W.Werner, H.Dreizler, and H.D.Rudolph, Z.Naturforsch. 22a,531(1967).

 








 








1,2,4-Triazine 1,2,3-Triazine 1,3,5-Triazine

 








 








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Molecules/Nitrogen




 








 













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Last Modified 14 Feb 2015